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MIDIDecoder: Convert return value of readContinuedValue into a std::optional 

Rather than use an out reference, we can convert the return value into a
std::optional, combining the out reference and boolean return value into
one.
This commit is contained in:
Lioncash 2019-08-24 22:44:31 -04:00
parent 64fbb923ca
commit e48a094198
1 changed files with 19 additions and 16 deletions
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35
lib/audiodev/MIDIDecoder.cpp
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@ -1,6 +1,7 @@
#include "boo/audiodev/MIDIDecoder.hpp" #include "boo/audiodev/MIDIDecoder.hpp"
#include <algorithm> #include <algorithm>
#include <optional>
#include "boo/audiodev/IMIDIReader.hpp" #include "boo/audiodev/IMIDIReader.hpp"
#include "lib/audiodev/MIDICommon.hpp" #include "lib/audiodev/MIDICommon.hpp"
@ -10,28 +11,30 @@ namespace boo {
namespace { namespace {
constexpr uint8_t clamp7(uint8_t val) { return std::max(0, std::min(127, int(val))); } constexpr uint8_t clamp7(uint8_t val) { return std::max(0, std::min(127, int(val))); }
bool readContinuedValue(std::vector<uint8_t>::const_iterator& it, std::vector<uint8_t>::const_iterator end, std::optional<uint32_t> readContinuedValue(std::vector<uint8_t>::const_iterator& it,
uint32_t& valOut) { std::vector<uint8_t>::const_iterator end) {
uint8_t a = *it++; uint8_t a = *it++;
valOut = a & 0x7f; uint32_t valOut = a & 0x7f;
if (a & 0x80) { if ((a & 0x80) != 0) {
if (it == end) if (it == end) {
return false; return std::nullopt;
}
valOut <<= 7; valOut <<= 7;
a = *it++; a = *it++;
valOut |= a & 0x7f; valOut |= a & 0x7f;
if (a & 0x80) { if ((a & 0x80) != 0) {
if (it == end) if (it == end) {
return false; return std::nullopt;
}
valOut <<= 7; valOut <<= 7;
a = *it++; a = *it++;
valOut |= a & 0x7f; valOut |= a & 0x7f;
} }
} }
return true; return valOut;
} }
} // Anonymous namespace } // Anonymous namespace
@ -52,9 +55,8 @@ std::vector<uint8_t>::const_iterator MIDIDecoder::receiveBytes(std::vector<uint8
return begin; return begin;
a = *it++; a = *it++;
uint32_t length; const auto length = readContinuedValue(it, end);
readContinuedValue(it, end, length); it += *length;
it += length;
} else { } else {
uint8_t chan = m_status & 0xf; uint8_t chan = m_status & 0xf;
switch (Status(m_status & 0xf0)) { switch (Status(m_status & 0xf0)) {
@ -125,10 +127,11 @@ std::vector<uint8_t>::const_iterator MIDIDecoder::receiveBytes(std::vector<uint8
case Status::SysEx: { case Status::SysEx: {
switch (Status(m_status & 0xff)) { switch (Status(m_status & 0xff)) {
case Status::SysEx: { case Status::SysEx: {
uint32_t len; const auto len = readContinuedValue(it, end);
if (!readContinuedValue(it, end, len) || end - it < len) if (!len || end - it < *len) {
return begin; return begin;
m_out.sysex(&*it, len); }
m_out.sysex(&*it, *len);
break; break;
} }
case Status::TimecodeQuarterFrame: { case Status::TimecodeQuarterFrame: {